While today is Microsoft's big launch day for Windows Mobile 6.5, the response and reviews have generally been tepid. But HTC's HD2 smartphone may make even the most diehard iPhone fanatic give Windows Mobile a chance.The device packs a massive 4.3-inch capacitive touch screen that dwarfs the iPhone and most other touch devices. This is definitely flirting with almost being too big for a pocket, but I had a chance to briefly play with the first version (which packed a 3.8 screen) and found the larger size fine. The capacitive screen means it should be as responsive as most modern touch screens, and HTC has added some multi-touch capabilities as well.

The screen will be the first thing you notice, but it's what inside that makes this device drool-worthy. The HD2 packs a 1 GHz Snapdragon-based processor, and this means it has plenty of horsepower to multitask and perform well. HTC has also thrown its Sense UI on top of Windows Mobile and have reportedly made a ton of software tweaks to make sure the HD2 is blazing fast. There's also Wi-Fi, GPS, 3G, a 5-megapixel camera, and a standard headphone jack.

Microsoft's held an open house event in New York today showcasing Windows Mobile 6.5 devices, and the HD2 was in the house. The scamps at Engadget got some hands-on time and were impressed.

We were frankly blown away with how slick this phone is. Mind you, WM 6.5 still shows its not-so-fresh colors here and there, but he general experience of using the device is handled mainly through the Sense interface, and it blows the hinges off of any other Windows phone experience we've had. Ever. From the lag-free gestures which get you around the device, to image pinching and zooming with that aforementioned multitouch, the hesitation-free jumps in and out of applications, and typing on the sprawling, HTC-ified onscreen keyboard, using the HD2 is a joy.

The first HTC HD never came out officially in the United States, but HTC officials are saying it will be here in the first quarter of 2010. That's still plenty far away, and there's no word on if this will come with a carrier subsidy, but Windows Mobile fans will soon have their own lust-worthy device.